1. Field of the Invention
Embodiments of the invention described herein pertain to the field of computer systems. More particularly, but not by way of limitation, one or more embodiments of the invention enable a system and method for periodic body scan differencing for detecting changes in surface and subsurface body scans over time.
2. Description of the Related Art
There are many types of methods for scanning a biological specimen, such as a body. Methods include introducing energy to a body and recording energy that transmits through a body or reflects back from a body. These methods are utilized for subsurface scanning and surface scanning. Generally, the methods are directed at diagnosing or investigating ailments or functions of a body. One type of scanning includes medical imaging. Medical imaging includes radiological, thermographic, photographic, microscopic and acoustic imaging. Within the medical imaging area, morphological tissue imaging is utilized to observe changes in tissues.
X-ray scanning may be utilized for both subsurface and surface scanning. Subsurface scanning using x-rays has been utilized for many years to scan the body for broken bones for example. X-rays may also be utilized for surface scanning, as in the case of backscatter scanning devices. Backscatter devices have been controversial in their proposed use for airport security due to the invasion of privacy, i.e., of a scanner capable of viewing through clothing for example.
Current efforts in early detection of diseases include whole body computed tomography (CT) scanning. CT scanning is also known as computerized axial tomography (CAT). The United States Food and Drug administration currently does not recommend whole body CT scanning as the radiation risks are thought to outweigh the remote possibility of detecting a disease early enough to cure the disease. The dose of x-rays received during a whole body CT scan is far greater than a typical chest x-ray. A CT scan of the stomach for example is generally equivalent to 500 chest x-rays or about the same amount of radiation received from the background in over 3 years. CT scans generally produce images of thin slices of a body. Imaging by slices is an example of a tomographic imaging solution. CT scans show good detail when imaging dense tissues and bones since this technique relies on the blocking of x-rays to generate an image.
Positron-emission tomography (PET) allows for the capability to detect gamma rays emitted from a positron-emitting isotope introduced into a body. Depending on the molecule introduced, different tissues of interest may be scanned. One common molecule utilized in PET is fluorodeoxyglucose (FDG) a type of sugar that accumulates in glucose-avid cells, including tumor cells for example. Generally tumors smaller than 5 mm are undetectable using PET scans. Hence, there are limitations with this type of technology with respect to morphological tissue imaging.
Magnetic resonance imaging (MRI) uses powerful electromagnets to excite hydrogen nuclei. MRI's usually create two-dimensional slices through a body. Unlike x-rays, MRI's do not use ionizing radiation and therefore do not have the same health issues. MRI's also have the advantage of showing good detail in soft tissues. MRI's have poor resolution with respect to morphological tissue imaging for small details.
Optical coherence tomography (OCT) on the other hand utilizes lower frequency electromagnetic radiation than x-rays, for example light from a laser. The frequency of radiation generally utilized is not high enough to damage DNA and as such, is much safer than x-rays. Generally, the item being scanned must allow for at least a small percentage of photons to travel through it. This technology allows for resolution on the order of a micron or less and is well suited for use in morphological tissue imaging.
Confocal microscopy is an improved version of convention microscopy that utilizes a point source for light and gathers an image from the focal plane of the microscope. This imaging technique lacks millimeter penetration depth and is not utilized in morphological tissue imaging.
Multispectral colposcopy is a technique for surface scanning tissue at multiple frequencies to better detect subtle changes or abnormalities, for example of the human cervix. This technique is an improvement over standard colposcopy as performed visually that is highly dependent on the physician's visual acuity and expertise.
Medical ultrasonography is another scanning technology for imaging a body. Medical sonography is also known as ultrasound. Ultrasound is commonly utilized to image a fetus in the womb during pregnancy for example. Ultrasound is so name since the frequency of energy utilized is above 20,000 Hertz, i.e., above the upper limit of human hearing. Generally, ultrasound scanners work in the Megahertz range, for example between 2 and 18 Megahertz. Ultrasound scans of lower frequency sound provide less resolution but penetrate deeper into the body while higher frequency scans provide more resolution yet do not penetrate as deep into the body. Ultrasound has poor resolution with respect to morphological tissue imaging.
Regardless of the technology utilized to generate a scan of a portion of a body, recurrence testing and morphological tissue imaging generally utilize a pair of side by side images that are visually compared by a doctor. The images include a first image taken at a previous doctor visit and a new image taken at the current doctor visit. The doctor looks at the images side by side to determine if there are new problems. This technique applies to surface and subsurface scans. Depending on the type of imaging technology and resulting images, many dangerous tissue changes go undetected based on the visual acuity of the particular doctor manually comparing the two images side by side. Hence, there is a need for an system and method for periodic body scan differencing that can detect subtle changes in the surface or subsurface of a body over time with a sensitivity greater than the current side by side comparison with the human eye in use today.